a29815a333
The list macros use LIST_POISON1 and LIST_POISON2 as undereferencable pointers in order to trap erronous use of freed list_heads. Unfortunately userspace can arrange for those pointers to actually be dereferencable, potentially turning an oops to an expolit. To avoid this allow architectures (currently x86_64 only) to override the default values for these pointers with truly-undereferencable values. This is easy on x86_64 as the virtual address space is large and contains areas that cannot be mapped. Other 64-bit architectures will likely find similar unmapped ranges. [ingo: switch to 0xdead000000000000 as the unmapped area] [ingo: add comments, cleanup] [jaswinder: eliminate sparse warnings] Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
89 lines
2.5 KiB
C
89 lines
2.5 KiB
C
#ifndef _LINUX_POISON_H
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#define _LINUX_POISON_H
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/********** include/linux/list.h **********/
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/*
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* Architectures might want to move the poison pointer offset
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* into some well-recognized area such as 0xdead000000000000,
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* that is also not mappable by user-space exploits:
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*/
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#ifdef CONFIG_ILLEGAL_POINTER_VALUE
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# define POISON_POINTER_DELTA _AC(CONFIG_ILLEGAL_POINTER_VALUE, UL)
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#else
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# define POISON_POINTER_DELTA 0
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#endif
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/*
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* These are non-NULL pointers that will result in page faults
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* under normal circumstances, used to verify that nobody uses
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* non-initialized list entries.
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*/
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#define LIST_POISON1 ((void *) 0x00100100 + POISON_POINTER_DELTA)
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#define LIST_POISON2 ((void *) 0x00200200 + POISON_POINTER_DELTA)
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/********** include/linux/timer.h **********/
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/*
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* Magic number "tsta" to indicate a static timer initializer
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* for the object debugging code.
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*/
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#define TIMER_ENTRY_STATIC ((void *) 0x74737461)
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/********** mm/debug-pagealloc.c **********/
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#define PAGE_POISON 0xaa
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/********** mm/slab.c **********/
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/*
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* Magic nums for obj red zoning.
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* Placed in the first word before and the first word after an obj.
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*/
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#define RED_INACTIVE 0x09F911029D74E35BULL /* when obj is inactive */
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#define RED_ACTIVE 0xD84156C5635688C0ULL /* when obj is active */
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#define SLUB_RED_INACTIVE 0xbb
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#define SLUB_RED_ACTIVE 0xcc
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/* ...and for poisoning */
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#define POISON_INUSE 0x5a /* for use-uninitialised poisoning */
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#define POISON_FREE 0x6b /* for use-after-free poisoning */
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#define POISON_END 0xa5 /* end-byte of poisoning */
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/********** arch/$ARCH/mm/init.c **********/
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#define POISON_FREE_INITMEM 0xcc
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/********** arch/ia64/hp/common/sba_iommu.c **********/
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/*
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* arch/ia64/hp/common/sba_iommu.c uses a 16-byte poison string with a
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* value of "SBAIOMMU POISON\0" for spill-over poisoning.
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*/
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/********** fs/jbd/journal.c **********/
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#define JBD_POISON_FREE 0x5b
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#define JBD2_POISON_FREE 0x5c
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/********** drivers/base/dmapool.c **********/
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#define POOL_POISON_FREED 0xa7 /* !inuse */
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#define POOL_POISON_ALLOCATED 0xa9 /* !initted */
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/********** drivers/atm/ **********/
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#define ATM_POISON_FREE 0x12
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#define ATM_POISON 0xdeadbeef
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/********** net/ **********/
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#define NEIGHBOR_DEAD 0xdeadbeef
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#define NETFILTER_LINK_POISON 0xdead57ac
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/********** kernel/mutexes **********/
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#define MUTEX_DEBUG_INIT 0x11
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#define MUTEX_DEBUG_FREE 0x22
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/********** lib/flex_array.c **********/
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#define FLEX_ARRAY_FREE 0x6c /* for use-after-free poisoning */
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/********** security/ **********/
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#define KEY_DESTROY 0xbd
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/********** sound/oss/ **********/
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#define OSS_POISON_FREE 0xAB
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#endif
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